Normally, printers and typewriters are designed for printing on sheets of paper, usually of the format A4, said sheets being placed in the machine so as to present either the short or the long edge in the direction of feed. The machines are equipped with friction drive means including rollers or belts which co-operate with a platen or with idle rollers of a different kind for the feeding of a sheet of paper. Such machines are also used with continuous forms which have rows of holes along their side edges in the direction of feed and in which engage pin wheels provided for the driving of the said forms. Most often the pin wheel drive means are included in a separate unit connected to the machine, preferably in a way involving the inactivation of the friction drive means. The pin wheel drive means may include a separate drive motor or may be connected to the drive motor for the friction drive means.
The need for a separate unit when using continuous forms with existing printers and typewriters constitutes an obvious drawback.